Pump Device

ABSTRACT

A pump device has a motor rotation shaft and a pump rotation shaft whose end portion is connected to an end portion of the motor rotation shaft and which drives a pump unit. The pump device includes: an outer circumferential seal portion that is arranged at either one or both of radially outer sides of the end portion of the pump rotation shaft and the end portion of the motor rotation shaft so as to overlap with either one or both of the end portion of the pump rotation shaft and the end portion of the motor rotation shaft in axial directions of the pump rotation shaft and the motor rotation shaft and has an outer circumferential seal surface; and a seal unit that makes sliding contact with the outer circumferential seal portion.

BACKGROUND OF THE INVENTION

The present invention relates to a pump device.

As a related art pump device provided with a seal unit at an end portion of a pump rotation shaft that is connected to a motor rotation shaft and drives a pump unit, for instance, it has been disclosed in Japanese Patent Provisional Publication No. 2007-278086 (hereinafter is referred to as “JP2007-278086”). The pump device of JP2007-278086 has a seal member to seal the pump unit, which prevents leak of brake fluid from the pump unit.

SUMMARY OF THE INVENTION

In JP2007-278086, however, there is a possibility that a size of the pump device will increase in an axial direction.

It is therefore an object of the present invention to provide a pump device that is capable of suppressing the increase in size of the pump device in the axial direction.

According to one aspect of the present invention, a pump device having a motor rotation shaft and a pump rotation shaft whose end portion is connected to an end portion of the motor rotation shaft and which drives a pump unit, the pump device comprises: an outer circumferential seal portion that is arranged at either one or both of radially outer sides of the end portion of the pump rotation shaft and the end portion of the motor rotation shaft so as to overlap with either one or both of the end portion of the pump rotation shaft and the end portion of the motor rotation shaft in axial directions of the pump rotation shaft and the motor rotation shaft and has an outer circumferential seal surface; and a seal unit that makes sliding contact with the outer circumferential seal portion.

According to another aspect of the present invention, a pump device comprises: a motor rotation shaft; a pump rotation shaft that is connected to the motor rotation shaft through a connecting portion of the pump rotation shaft and drives a pump unit; and a seal unit that suppresses a leak of working fluid from the pump unit along an outer circumference of the pump rotation shaft, and the connecting portion of the pump rotation shaft is located at a radially inner side of the seal unit.

According to a further aspect of the invention, a pump device comprises: a housing; a motor that is fixed to the housing and drives a pump unit provided in the housing, the motor having a motor rotation shaft that is connected to a pump rotation shaft of the pump unit through a connecting portion of the pump rotation shaft and drives the pump unit; a cylindrical collar member that covers the connecting portion of the pump rotation shaft; a seal unit that makes sliding contact with an outer circumferential surface of the cylindrical collar member; and a seal unit retaining hole that is formed in the housing and retains therein the seal unit.

The other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general perspective view of a brake apparatus to which a pump device of an embodiment 1 is applied.

FIG. 2 is an axial direction sectional view of the pump device of the embodiment 1.

FIG. 3 is an axial direction sectional view of a pump device of the embodiment 2.

FIG. 4 is an axial direction sectional view of a pump device of the embodiment 3.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of a pump device of the present invention will be explained below with reference to the drawings.

Embodiment 1

FIG. 1 is a general perspective view of a brake apparatus 10 to which a pump device 1 of an embodiment 1 is applied.

The brake apparatus 10 produces a braking force by providing a brake fluid pressure to each wheel of a vehicle. The brake apparatus 10 has a hydraulic unit 11 disposed between a master cylinder (not shown) that generates a hydraulic pressure in response to driver's brake pedal operation and a wheel cylinder (not shown) that is provided at each wheel.

The hydraulic unit 11 has a brake fluid pressure circuit in a housing 110, also is provided with the pump device 1 and an electromagnetic valve. The hydraulic unit 11 serves as a brake fluid pressure generator that can generate a wheel cylinder pressure (the brake fluid pressure) independently of the driver's brake pedal operation by being provided with brake fluid from a brake fluid source (a reservoir or the master cylinder). The hydraulic unit 11 is configured as an electrical mechanical integrated unit in which a motor 12 for driving the pump device 1 is fixedly connected to the hydraulic unit 11 and an electronic control unit 13 for controlling an operation of the hydraulic unit 11 is integrally connected to the hydraulic unit 11. The hydraulic unit 11 is fixed to a vehicle body side through a bracket 14, then the brake apparatus 10 as a unit is mounted in an engine room of the vehicle.

FIG. 2 is an axial direction sectional view of the pump device 1, which shows a partial cross section of the pump device 1 cut by a plane passing through a shaft center of a pump rotation shaft 30 (a driving shaft 30 a and a driven shaft 30 b). In the drawings, a direction in which the pump rotation shaft 30 (or a motor rotation shaft 120) extends is defined as an X-axis, and a side of the motor 12 in the pump device 1 is defined as a positive direction side.

The pump device 1 is housed, as a pump assembly, in a housing hole 111 of the housing 110. The pump device 1 has a pump housing (a pump casing) 2, a pump unit 3 provided in the pump housing 2 and a seal unit 4 suppressing a flow of hydraulic fluid (working fluid) that leaks from the pump unit 3 along an outer circumference of the rotation shaft 30 (the driving shaft 30 a).

The motor 12 is fixed to the pump housing 2 (or the housing 110), and drives the pump unit 3. The motor 12 has the motor rotation shaft 120. An end portion 121, at an X-axis negative direction side, of the motor rotation shaft 120 is connected to the rotation shaft 30 (the driving shaft 30 a). By the fact that the motor rotation shaft 120 drives and rotates the driving shaft 30 a, the pump unit 3 is driven. The end portion 121 has a substantially square pole shape that is formed by cutting both opposing sides, positioned on opposite sides of a shaft center of the motor rotation shaft 120, of a cylindrical column.

The pump housing 2 has a first housing (a front case) 21, a second housing (a center plate) 22 and a third housing (a rear case) 23.

In the first housing 21, a shaft housing hole 210, a bearing retaining hole 211 and a first pump housing hole 212 are formed. The shaft housing hole 210 has a first shaft housing hole 210 a and a second shaft housing hole 210 b. Each X-axis negative direction side of the first and second shaft housing holes 210 a, 210 b is covered or closed by a bottom portion 21 a of the first housing 21, then each closed space is formed. The bearing retaining hole 211 has a first bearing retaining hole 211 a and a second bearing retaining hole 211 b. The first bearing retaining hole 211 a is formed substantially coaxially (concentrically) with the first shaft housing hole 210 a, and the second bearing retaining hole 211 b is formed substantially coaxially (concentrically) with the second shaft housing hole 210 b. The first bearing retaining hole 211 a retains therein a first bearing 7 a. The second bearing retaining hole 211 b retains therein a second bearing 7 b.

In the second housing 22, a penetration hole 220 is formed in the X-axis direction, and a seal member retaining hole 221 and a second pump housing hole 222 are formed. The penetration hole 220 has a first penetration hole 220 a and a second penetration hole 220 b. The seal member retaining hole 221 has a first seal member retaining hole 221 a and a second seal member retaining hole 221 b. The first seal member retaining hole 221 a is formed substantially coaxially (concentrically) with the first penetration hole 220 a, and the second seal member retaining hole 221 b is formed substantially coaxially (concentrically) with the second penetration hole 220 b. The first seal member retaining hole 221 a retains therein a first seal member 8 a through a retainer (a retaining member) 80 a. The second seal member retaining hole 221 b retains therein a second seal member 8 b through a retainer (a retaining member) 80 b.

In third housing 23, a penetration hole 230 is formed in the X-axis direction, and a bearing retaining hole 231, a seal unit retaining hole 232 and a motor setting hole 233 are formed. The bearing retaining hole 231 has a third bearing retaining hole 231 a that is formed substantially coaxially (concentrically) with the penetration hole 230 and a fourth bearing retaining hole 231 b. The third bearing retaining hole 231 a retains therein a third bearing 9 a. The fourth bearing retaining hole 231 b retains therein a fourth bearing 9 b. Here, the first to fourth bearings 7 a, 7 b, 9 a, 9 b are needle bearings in which a plurality of rollers are retained in a retainer. As the bearing, not only this roller bearing but, for instance, a ball bearing could be used as well.

The seal unit retaining hole 232 is formed in an outer peripheral area of an X-axis positive direction end portion of the third housing 23. More specifically, the seal unit retaining hole 232 is formed substantially coaxially (concentrically) with the penetration hole 230 at an X-axis positive direction side with respect to the third bearing retaining hole 231 a. The seal unit retaining hole 232 is formed into a cylindrical shape having a large diameter that is larger than a diameter of the penetration hole 230 (a body of the penetration hole 230). The seal unit retaining hole 232 has, at an X-axis negative direction side thereof, a bottom portion 234. The seal unit retaining hole 232 retains therein the seal unit 4 through a retainer (a retaining member) 42.

The motor setting hole 233 has a large diameter that is larger than the diameter of the seal unit retaining hole 232. The motor setting hole 233 is formed substantially coaxially (concentrically) with the penetration hole 230 with the motor setting hole 233 adjoining an X-axis positive direction side of the seal unit retaining hole 232. The motor setting hole 233 opens at the X-axis positive direction end portion of the third housing 23. An X-axis negative direction side protrusion (a bearing retaining portion of the motor rotation shaft 120) 12 a of the motor 12 is fitted into the motor setting hole 233. Then in this state, the end portion 121 of the motor rotation shaft 120 protrudes in the seal unit retaining hole 232.

The first housing 21, the second housing 22 and the third housing 23 are joined together in this order from the X-axis negative direction side, thereby forming the substantially cylindrical pump housing 2.

The first pump housing hole 212 of the first housing 21 forms a closed space by the fact that an X-axis positive direction side opening of the first pump housing hole 212 is covered or closed by an X-axis negative direction end surface of the second housing 22. The second pump housing hole 222 of the second housing 22 forms a closed space by the fact that an X-axis positive direction side opening of the second pump housing hole 222 is covered or closed by an X-axis negative- direction end surface of the third housing 23.

Annular seal grooves 212, 223, 235 are provided on an outer circumferential surface of the first housing 21, an outer circumferential surface of the second housing 22 and an outer circumferential surface of the third housing 23 respectively. Further, seal members 24, 25, 26 are fitted into the seal grooves 212, 223, 235 respectively. The seal members 24, 25, 26 are made contact with or touch an inner circumferential surface of the housing hole 111 of the housing 110, thereby liquid-tightly defining an inlet passage (not shown) and an outlet passage (not shown) between the inner circumferential surface of the housing hole 111 and the outer circumferential surface of the pump housing 2.

The third housing 23 is provided, at an outer circumference of the X-axis positive direction end portion thereof, with a brim portion 236. By the fact that the brim portion 236 is fitted into and made contact with a stepped portion 112 that is formed at an X-axis positive direction end of the housing hole 111 of the housing 110, positioning in the X-axis direction of the pump housing 2 (the pump device 1) with respect to the housing 110 is made.

The pump device 1 is a so-called tandem external gear pump, and the pump unit 3 has a first pump 31 and a second pump 32. The first pump 31 and the second pump 32 pump up and discharge the working fluid for different pipeline of the brake apparatus 10.

The first pump 31 has a first drive gear 31 a and a first driven gear 31 b that is engaged with the first drive gear 31 a, and the first pump 31 is housed in the first pump housing hole 212. A pair of side plates 311, 312 are provided at axial direction both ends of the first drive gear 31 a and the first driven gear 31 b. Further, a first penetration hole 313 a and a second penetration hole 313 b are formed at the X-axis negative direction side first side plate 311 so as to penetrate the first side plate 311 in the X-axis direction. On the other hand, a first penetration hole 314 a and a second penetration hole 314 b are formed at the X-axis positive direction side second side plate 312 so as to penetrate the second side plate 312 in the X-axis direction. Both side plates 311, 312 seal predetermined areas of axial direction both end surfaces of the first drive gear 31 a and the first driven gear 31 b, and also partly seal tooth tips of the first drive gear 31 a and the first driven gear 31 b, thereby liquid-tightly defining a low-pressure chamber communicating with the inlet passage (not shown) and a high-pressure chamber (P1, P2) communicating with the outlet passage (not shown).

A seal groove 315 a is formed at an outer circumference of an X-axis negative direction end surface of the first side plate 311, and a seal member 315 is fitted onto the seal groove 315 a. The seal member 315 is made contact with or touches an X-axis negative direction side bottom portion of the first pump housing hole 212, also forces the first side plate 311 in the X-axis positive direction, thereby improving liquid-tightness between the low-pressure chamber and the high-pressure chamber. Likewise, a seal groove 316 a is formed at an outer circumference of an X-axis positive direction end surface of the second side plate 312, and a seal member 316 is fitted onto the seal groove 316 a. The seal member 316 is made contact with or touches the X-axis negative direction end surface of the second housing 22, also forces the second side plate 312 in the X-axis negative direction, thereby improving the liquid-tightness between the low-pressure chamber and the high-pressure chamber.

The second pump 32 has a second drive gear 32 a and a second driven gear 32 b that is engaged with the second drive gear 32 a, and the second pump 32 is housed in the second pump housing hole 222. A pair of side plates 321, 322 are provided at axial direction both ends of the second drive gear 32 a and the second driven gear 32 b. Further, a first penetration hole 323 a and a second penetration hole 323 b are formed at the X-axis negative direction side first side plate 321 so as to penetrate the first side plate 321 in the X-axis direction. On the other hand, a first penetration hole 324 a and a second penetration hole 324 b are formed at the X-axis positive direction side second side plate 322 so as to penetrate the second side plate 322 in the X-axis direction. The first and second side plates 321, 322 have the same function as that of the first and second side plates 311, 312 of the first pump 31. In addition, seal members 325, 326 having the same function as that of the seal members 315, 316 of the first pump 31 are provided.

The pump unit 3 has the pump rotation shaft 30. The pump rotation shaft 30 has the driving shaft (a first pump rotation shaft) 30 a and the driven shaft (a second pump rotation shaft) 30 b.

The first and second drive gears 31 a, 32 a are joined to the driving shaft 30 a (in a whirl-stop connecting manner) by pins 33 a, 34 a respectively, and the driving shaft 30 a drives and rotates the first and second drive gears 31 a, 32 a. The first and second driven gears 31 b, 32 b are joined to the driven shaft 30 b (in a whirl-stop connecting manner) by pins 33 b, 34 b respectively.

More specifically, recessed portions 310 a, 320 a are formed at inner circumferences of penetration holes of the first and second drive gears 31 a, 32 a where the driving shaft 30 a penetrates, throughout an axial direction entire area of the first and second drive gears 31 a, 32 a. The cylindrical column pins 33 a, 34 a that extend in a radial direction from the driving shaft 30 a are fitted into the recessed portions 310 a, 320 a respectively. Each of the pins 33 a, 34 a could be fixed by press fitting. Or alternatively, each of the pins 33 a, 34 a might be fixed only by insertion of the pin. These fixing manners are not especially limited.

With respect to the first and second driven gears 31 b, 32 b, these fixing manners are the same as the above manners.

The first shaft housing hole 210 a (the first bearing retaining hole 211 a) of the first housing 21, the first penetration hole 313 a of the first side plate 311 and the first penetration hole 314 a of the second side plate 312 of the first pump 31, the first penetration hole 220 a (the first seal member retaining hole 221 a) of the second housing 22, the first penetration hole 323 a of the first side plate 321 and the first penetration hole 324 a of the second side plate 322 of the second pump 32, and the penetration hole 230 (the third bearing retaining hole 231 a, the seal unit retaining hole 232 and the motor setting hole 233) of the third housing 23 are arranged substantially coaxially (concentrically) with each other. Then the driving shaft 30 a is housed and set in these holes. The driving shaft 30 a is rotatably inserted in these holes with certain radial direction gaps between the driving shaft 30 a and the penetration holes 220 a, 230, 313 a etc. provided.

The driving shaft 30 a is supported at an axial direction one end portion on an X-axis negative direction side of the first drive gear 31 a of the first pump 31 by the first bearing 7 a so as to be able to rotate with respect to the first housing 21, also is supported at an axial direction other end portion on an X-axis positive direction side of the second drive gear 32 a of the second pump 32 by the third bearing 9 a so as to be able to rotate with respect to the third housing 23.

An outer circumferential surface of the driving shaft 30 a, positioned at a middle portion between the first drive gear 31 a of the first pump 31 and the second drive gear 32 a of the second pump 32, makes sliding contact with a drive side shaft seal member (the first seal member) 8 a.

The second shaft housing hole 210 b (the second bearing retaining hole 211 b) of the first housing 21, the second penetration hole 313 b of the first side plate 311 and the second penetration hole 314 b of the second side plate 312 of the first pump 31, the second penetration hole 220 b (the second seal member retaining hole 221 b) of the second housing 22, the second penetration hole 323 b of the first side plate 321 and the second penetration hole 324 b of the second side plate 322 of the second pump 32, and the fourth bearing retaining hole 231 b of the third housing 23 are arranged substantially coaxially (concentrically) with each other. Then the driven shaft 30 b is housed and set in these holes. The driven shaft 30 b is rotatably inserted in these holes with certain radial direction gaps between the driven shaft 30 b and the penetration holes 220 b, 313 b etc. provided.

The driven shaft 30 b is supported at an axial direction one end portion on an X-axis negative direction side of the first driven gear 31 b of the first pump 31 by the second bearing 7 b so as to be able to rotate with respect to the first housing 21, also is supported at an axial direction other end portion on an X-axis positive direction side of the second driven gear 32 b of the second pump 32 by the fourth bearing 9 b so as to be able to rotate with respect to the third housing 23.

An outer circumferential surface of the driven shaft 30 b, positioned at a middle portion between the first driven gear 31 b of the first pump 31 and the second driven gear 32 b of the second pump 32, makes sliding contact with a driven side shaft seal member (the second seal member) 8 b.

An X-axis positive direction side of the driving shaft 30 a is formed into a stepped shape and has a substantially cylindrical column having a different diameter. More specifically, an X-axis positive direction side end portion 300 of the driving shaft 30 a is formed into the substantially cylindrical column, and its diameter is formed to be smaller than that of the other portion of the driving shaft 30 a. In this way, the driving shaft 30 a has a stepped portion 302 that is formed by the fact that the diameter of the X-axis positive direction side (the end portion 300) is formed to be smaller. The diameter of the driving shaft 30 a (except the end portion 300) (i.e. a large diameter side of the stepped portion 302) is set to be smaller than that of the penetration hole 230 of the third housing 23.

The stepped portion 302 is positioned at a slightly X-axis negative direction side (in the penetration hole 230) with respect to the seal unit retaining hole 232, and the end portion 300 protrudes in the seal unit retaining hole 232, in a state in which the driving shaft 30 a is housed in the penetration hole 230 etc. of the pump housing 2.

The end portion 300 has a connecting portion 301 that is connected to the end portion 121 of the motor rotation shaft 120. The driving shaft 30 a is connected to the motor rotation shaft 120 through this connecting portion 301, and drives the pump unit 3 (the first pump 31 and the second pump 32).

A collar member 5 is provided at an outer circumference of the connecting portion 301. Then the seal unit 4 makes sliding contact with an outer circumferential surface of the collar member 5. That is, the connecting portion 301 is a section or a member where the collar member 5 is provided at the end portion 300, and the connecting portion 301 is located at a radially inner side of the seal unit 4.

The collar member 5 is formed into a cylindrical shape that covers or surrounds the connecting portion 301, and is fixedly connected to the driving shaft 30 a. More specifically, the collar member 5 is provided, at an X-axis negative direction side inner circumference thereof, with a substantially cylindrical driving shaft insertion hole 51. By the fact that the end portion 300 is press-fitted into this driving shaft insertion hole 51, the collar member 5 is press-fixed to the end portion 300.

Further, the collar member 5 is formed into a cylindrical shape that covers or surrounds the end portion 121 of the motor rotation shaft 120, and is connected to the end portion 121 in a whirl-stop connecting manner. More specifically, the collar member 5 is provided, at an X-axis positive direction side inner circumference thereof, with a motor rotation shaft insertion hole 52 whose shape is a substantially same as the substantially square pole shape of the end portion 121. Then by the fact that the end portion 121 is fitted into this motor rotation shaft insertion hole 52, the collar member 5 is connected to the end portion 121 in the whirl-stop connecting manner. Here, as long as the end portion 121 and the collar member 5 are connected together in the whirl-stop connecting manner, shapes of these end portion 121 and collar member 5 are not limited to shapes of the embodiment 1.

In this manner, the collar member 5 is provided at the outer circumference of the end portion 300 of the driving shaft 30 a and at an outer circumference of the end portion 121 of the motor rotation shaft 120 with the collar member 5 ranging from the end portion 300 to the end portion 121. The motor rotation shaft 120 is connected to the driving shaft 30 a through the end portion 121 as a connecting portion, and the collar member 5 covers or surrounds this connecting portion (the end portion 121). Thus, the connecting portion (the end portion 121) of the motor rotation shaft 120 is located at the radially inner side of the seal unit 4.

The collar member 5 is provided, at an outer circumference thereof, with a substantially cylindrical outer circumferential seal portion 50. The outer circumferential seal portion 50 has an outer circumferential seal surface 500 that is an outer circumferential surface of the collar member 5. The outer circumferential seal portion 50 (the outer circumferential seal surface 500) is positioned at a radially outer side of the end portion 300 (the connecting portion 301) so as to overlap with the end portion 300 (the connecting portion 301) in the axial direction of the driving shaft 30 a. That is, the outer circumferential seal portion 50 (the outer circumferential seal surface 500) is positioned at the radially outer side of the end portion 300 so as to overlap with the end portion 300 (the connecting portion 301) when viewed from the radial direction of the driving shaft 30 a.

Likewise, the outer circumferential seal portion 50 (the outer circumferential seal surface 500) is positioned at a radially outer side of the end portion (the connecting portion) 121 of the motor rotation shaft 120 so as to overlap with the end portion (the connecting portion) 121 in the axial direction of the motor rotation shaft 120. That is, the outer circumferential seal portion 50 (the outer circumferential seal surface 500) is positioned at the radially outer side of the end portion (the connecting portion) 121 so as to overlap with the end portion (the connecting portion) 121 when viewed from a radial direction of the motor rotation shaft 120.

The seal unit 4 is set so as to make sliding contact with the outer circumferential seal surface 500 (the outer circumferential seal portion 50) of the collar member 5, then suppresses leak of the working fluid. The outer circumferential seal surface 500 functions as a sliding-contact seal surface with which the seal unit 4 makes sliding contact. As same as the collar member 5, the seal unit 4 is set in an area ranging from the end portion 300 to the end portion 121 in the X-axis direction.

The seal unit 4 has a seal member 40, a lip member 41 that is disposed in the axial direction (at an X-axis positive direction side) of the seal member 40, and a retaining member (an annular retainer) 42 that is a case retaining the seal member 40 and the lip member 41 (retaining an outer peripheral side of the seal member 40 and an outer peripheral side of the lip member 41). The seal member 40 suppresses the leak of the working fluid from an inside of the pump device 1 (from an inside of the pump unit 3) to the outside. The lip member 41 suppresses an external leak (or an outside leak) of the working fluid, which further leaks from the seal member 40 to the outside. This lip member 41 also has a function of suppressing entering of a foreign matter (dust etc.) to the inside of the pump device 1 (to the inside of the pump unit 3) from the outside.

The seal member 40 has a resin seal member body 400 that makes sliding contact with the outer circumferential seal portion 50 and an elastic member (e.g.

a rubber member) 401 that forces the seal member body 400 in a radially inward direction (in a direction toward the outer circumferential seal portion 50). As material of the elastic member 401, for instance, EPDM (ethylene propylen dien monomer) could be used.

The lip member 41 has an elastic lip member body (e.g. rubber lip member body) 410 that makes sliding contact with the outer circumferential seal portion 50 and a ring-shaped supporting member 411 to which the lip member body 410 is bonded by vulcanization bonding.

The retaining member 42 is formed into a substantially cylindrical shape. The retaining member 42 has a substantially ring-shaped bottom portion 420 that is formed by the fact that an axial direction one side (an X-axis positive direction side) end portion of the retaining member 42 is bent in the radially inward direction. The retaining member 42 is press-fitted into and fixed to the seal unit retaining hole 232.

Between the bottom portion 234 (at the X-axis negative direction side) of the seal unit retaining hole 232 and the seal unit 4, a disk member 6 is provided. The disk member 6 is formed by, for instance, metal material, and is formed as a single-piece member by pressing. The disk member 6 is a hollow or concave disk plate member sandwiched and supported between the bottom portion 234 and the seal unit 4. The disk member 6 has a penetration hole (a circle hole) 60 where the driving shaft 30 a (the end portion 300) having the smaller diameter penetrates. A diameter of the penetration hole 60 is set to be greater than the diameter of the end portion 300 (a small diameter side of the stepped portion 302) and also set to be smaller than the diameter of the driving shaft 30 a (the large diameter side of the stepped portion 302).

Further, the disk member 6 has an extending portion 62 formed so as to extend toward the X-axis positive direction, at a radial direction middle between an inner rim (a disk-shaped inner circumferential portion that surrounds the penetration hole 60) 61 of the penetration hole 60 and an outer circumferential portion 63.

The disk member 6 is set in the seal unit retaining hole 232 so that the inner circumferential portion (the inner rim) 61 and the outer circumferential portion 63 are made contact with or touch the bottom portion 234. More specifically, in a state in which the seal unit 4 is set in the seal unit retaining hole 232 (the retaining member 42 is press-fitted into and fixed to the seal unit retaining hole 232), the outer circumferential portion 63 of the disk member 6 is sandwiched and supported between an X-axis negative direction end portion of the retaining member 42 and the bottom portion 234. Furthermore, the extending portion 62 of the disk member 6 is made contact with or touches an X-axis negative direction end portion of the seal member body 400, and forces the seal member body 400 in the X-axis positive direction.

The seal member 40 and the lip member 41 are sandwiched and supported (retained) with these members 40, 41 made contact with each other between the extending portion 62 of the disk member 6 and the bottom portion 420 of the retaining member 42.

An X-axis negative direction end surface of the disk member 6 (the inner circumferential portion 61) faces an X-axis positive direction end surface of the stepped portion 302 of the driving shaft 30 a, whereas an X-axis positive direction end surface of the disk member 6 (the inner circumferential portion 61) faces an X-axis negative direction end surface of the collar member 5.

When the driving shaft 30 a is positioned at an ideal position of the assembly (at a neutral position in the X-axis direction) in the pump housing 2, an X-axis direction distance (or space) between the X-axis positive direction end surface of the stepped portion 302 of the driving shaft 30 a and the disk member 6 (the inner circumferential portion 61) is set to be smaller than an X-axis direction distance (or gap) between an X-axis negative direction end surface of the second side plate 312 of the first pump 31 and an X-axis positive direction end of the pin 33 a (also between an X-axis negative direction end surface of the second side plate 322 of the second pump 32 and an X-axis positive direction end of the pin 34 a).

Further, an X-axis direction distance (or space) between the X-axis negative direction end surface of the collar member 5 and the disk member 6 (the inner circumferential portion 61) is set to be greater than an X-axis direction distance (or gap) between an X-axis negative direction end surface of the driving shaft 30 a in the first shaft housing hole 210 a and the bottom portion 21 a of the first housing 21, and also is set to be smaller than an X-axis direction distance (or gap) between an X-axis positive direction end surface of the first side plate 311 of the first pump 31 and an X-axis negative direction end of the pin 33 a (also between an X-axis positive direction end surface of the first side plate 321 of the second pump 32 and an X-axis negative direction end of the pin 34 a).

Operation and Function of Embodiment 1

Next, operation and function of the pump device 1 will be explained.

When the pump rotation shaft 30 (the driving shaft 30 a) is driven and rotated by the motor 12, by the first and second drive gears 31 a, 32 a and the first and second driven gears 31 b, 32 b which are rotated by the engagement, the first pump 31 and the second pump 32 each pumps up the working fluid from the inlet passage through the low-pressure chamber and discharges the working fluid to the outlet passage through the high-pressure chamber (P1, P2).

The second housing 22 is a division wall (or a bulkhead) between the first pump 31 and the second pump 32, and there is a slight gap between an inner circumferential surface of the penetration hole 220 of the second housing 22 and the outer circumferential surface of the pump rotation shaft 30 (the driving shaft 30 a and the driven shaft 30 b) penetrating the penetration hole 220. In this configuration, there occurs leak of the working fluid between the first pump 31 and the second pump 32 through this gap.

For this leak, by the fact that the drive side shaft seal member (the first seal member) 8 a is set so as to make sliding contact with the outer circumferential surface of the driving shaft 30 a, and also the driven side shaft seal member (the second seal member) 8 b is set so as to make sliding contact with the outer circumferential surface of the driven shaft 30 b, the above leak of the working fluid is suppressed.

On the other hand, the third housing 23 where the motor 12 is mounted is provided with an opening (which communicates with the seal unit retaining hole 232 and the motor setting hole 233 and opens at the X-axis positive direction side) in which the motor rotation shaft 120 is connected to the driving shaft 30 a. Further, there is a slight gap between an inner circumferential surface of the penetration hole 230 of the third housing 23 and the outer circumferential surface of the driving shaft 30 a penetrating the penetration hole 230 (there is also a slight gap of the third bearing 9 a). Thus, there is a possibility that the working fluid will leak to the above opening from the first pump 31 (also the second pump 32) through this gap (these gaps) and leak to the outside of the pump housing 2.

For this leak, by the fact that the seal unit 4 is provided so as to make sliding contact with outer circumferential sides of the driving shaft 30 a and the motor rotation shaft 120, the above leak of the working fluid is suppressed.

The seal unit 4 is arranged so as to overlap with the driving shaft 30 a and the connecting portion (the end portion 121) of the motor rotation shaft 120 in the axial direction when viewed from the radial direction. With this arrangement, increase in size of the pump device 1 in the axial direction is suppressed. That is, an axial direction space required for the connection of the driving shaft 30 a and the motor rotation shaft 120 and an axial direction space required for installation of the seal member 40 etc. for suppressing the leak of the working fluid are provided as the same space (as a common space) (or, each part of these axial direction spaces is the same), thereby saving the axial direction space and reducing the required axial direction size of the pump device 1.

More specifically, the outer circumferential seal portion 50 with which the seal unit 4 makes sliding contact is set at the position where the seal unit 4 overlaps, when viewed from the radial direction, with the end portion 300 of the driving shaft 30 a which is connected to the end portion 121 of the motor rotation shaft 120 and/or at the position where the seal unit 4 overlaps, when viewed from the radial direction, with the end portion 121 of the motor rotation shaft 120 which is connected to the end portion 300 of the driving shaft 30 a. That is to say, in the embodiment 1, the outer circumferential seal portion 50 is provided with the outer circumferential seal portion 50 ranging from the outer circumferential side of the end portion 300 of the driving shaft 30 a to the outer circumferential side of the end portion 121 of the motor rotation shaft 120. However, as long as these end portions are an connecting end portion, the outer circumferential seal portion 50 could be provided only at the outer circumferential side of the driving shaft 30 a, or could be provided only at the outer circumferential side of the motor rotation shaft 120. Also in this case, it is possible to save the axial direction space required for installation of the seal member 40 etc. to some extent.

In the embodiment 1, the seal unit 4 is set in the area ranging from the end portion 300 of the driving shaft 30 a to the end portion 121 of the motor rotation shaft 120 in the X-axis direction. Therefore, a common area of the axial direction space required for the connection of the both shafts 30 a, 120 and the installation space of the seal unit 4 can be enlarged or increased, and the reduction of the axial direction size of the pump device 1 can be achieved more effectively.

The seal unit 4 is retained in the seal unit retaining hole 232 formed in the outer peripheral area of the X-axis positive direction end portion of the pump housing 2 (the third housing 23). Thus, the seal unit 4 can be readily set at the position where the seal unit 4 overlaps with the both connecting portions 301, 121 of the shafts 30 a, 120 in the axial direction when viewed from the radial direction. In addition, as compared with a case where the seal unit 4 is retained in a retaining hole that is formed at an inner side (at an X-axis negative direction side) with respect to the outer peripheral area of the X-axis positive direction end portion of the pump housing 2, the reduction of the axial direction size of the pump device 1 can be achieved.

The arrangement and configuration of the seal unit 4 is applied to the tandem type pump device 1 in which the two pumps 31, 32 are disposed in series on the same driving shaft 30 a. Because of this, an effect (a merit) of reduction of the axial direction size by the arrangement and configuration of the seal unit 4 becomes great. In other words, by employing the tandem type pump device having the two pumps, reduction in an overall size of the brake apparatus 10 can be achieved, and also by suppressing the axial direction size of the pump device 1 by the arrangement of the seal unit 4, further reduction in the overall size of the brake apparatus 10 can be achieved.

Here, except for the tandem type pump device, the arrangement and configuration of the seal unit 4 could be applied to a pump device having one pump.

Further, although the seal unit 4 has a dual (or double) seal structure in which the two seal members (the seal member 40 and the lip member 41) are provided, the dual seal structure is not necessarily employed. In the embodiment 1, by employing the dual seal structure, sealing performance can be enhanced.

The outer circumferential seal portion 50 is formed, at the outer circumferential sides of the both end portions 300, 121 of the shafts 30 a, 120, on the outer circumference of the collar member 5 ranging from the end portion 300 to the end portion 121. Therefore, even in the case where the seal unit 4 is arranged so as to overlap with the both connecting portions 301, 121 of the shafts 30 a, 120 in the axial direction when viewed from the radial direction (in the area ranging from the end portion 300 to the end portion 121), it is possible to easily form the outer circumferential seal portion 50 with which the seal unit 4 makes sliding contact.

The collar member 5 is provided as a different member from the driving shaft 30 a and the motor rotation shaft 120. Therefore, as compared with a case where the collar member 5 is provided as a same member as, e.g. the driving shaft 30 a namely that the collar member 5 is formed integrally with the driving shaft 30 a) (see an embodiment 3), design flexibility can be increased, and also assembly workability of the pump device 1 and ease of assembly of the pump device 1 and the motor 12 can be improved. That is, in the case where the collar member 5, whose diameter is greater than that of the X-axis positive direction side end portion 300 of the driving shaft 30 a, is formed integrally with the end portion 300, after the stepped portion 302 is formed at the driving shaft 30 a, it is difficult for the disk member 6 to be set at the X-axis positive direction side of the stepped portion 302 (at the X-axis negative direction side of the collar member 5).

In contrast to this, by providing the collar member 5 as the different member from the driving shaft 30 a, the disk member 6 can be easily set at the X-axis positive direction side of the stepped portion 302.

Further, in the case where the collar member 5, whose diameter is greater than that of the driving shaft 30 a, is formed integrally with the X-axis positive direction side end portion 300 of the driving shaft 30 a, it is required that after the driving shaft 30 a is inserted into the pump housing 2 (the third housing 23) from the X-axis positive direction side, each component be assembled from the opposite side (from the X-axis negative direction side).

In contrast to this, by providing the collar member 5 as the different member from the driving shaft 30 a, each component (except the seal unit 4, the collar member 5 and the disk member 6) of the pump device 1 can be assembled from one side (from the X-axis negative direction side). This improves the assembly workability of the pump device 1. Additionally, upon the assembly in which the pump device 1 is assembled separately from the seal unit 4, the collar member 5 and the disk member 6 (hereinafter called seal unit 4 etc.) then the pump device 1 and the motor 12 are connected together, it is possible to install the seal unit 4 etc. (it is possible to press-fit the seal unit 4 and the collar member 5). In other words, the pump device 1 can be handled as a separate assembly from the seal unit 4 etc., and also the seal unit 4 etc. can be handled as a separate assembly from this assembly of the pump device 1. Thus, ease of assembly of the pump device 1 and the motor 12 can be improved.

The collar member 5 is fixedly connected to the driving shaft 30 a. Thus, upon the assembly in which the pump device 1 and the motor 12 are connected together, only by engaging the motor rotation shaft 120 (the end portion 121) with the collar member 5 (fixedly connected to the driving shaft 30 a), the connection of the motor rotation shaft 120 and the driving shaft 30 a can be realized. Ease of assembly of the pump device 1 and the motor 12 can therefore be improved.

More specifically, the collar member 5 is provided as the different member from the driving shaft 30 a, and is press-fixed to the driving shaft 30 a. For example, in a case where the collar member 5 is fixed to the driving shaft 30 a with a screw etc. (see an embodiment 2), this requires a seal member to improve liquid-tightness of a fixation part of the screw etc.

In contrast to this, in the case of the press-fixing, since liquid-tightness of a press-fixed part is adequately ensured, no seal member is required, and parts count can be reduced.

Moreover, the collar member 5 is connected to the motor rotation shaft 120 in the whirl-stop connecting manner. Thus, upon the assembly in which the pump device 1 and the motor 12 are connected together, only by connecting the motor rotation shaft 120 to the collar member 5 (fixedly connected to the driving shaft 30 a) in the whirl-stop connecting manner, the connection of the motor rotation shaft 120 and the driving shaft 30 a can be realized. Ease of assembly of the pump device 1 and the motor 12 can therefore be improved. Here, the shape of the end portion 121 for the connection of the motor rotation shaft 120 and the collar member 5 in the whirl-stop connecting manner is not limited to shape of the embodiment 1.

Here, it is also possible to fixedly connect the collar member 5 to the motor rotation shaft 120 (e.g. by press-fitting) then connect the collar member 5 to the driving shaft 30 a in a whirl-stop connecting manner. In the embodiment 1, since the collar member 5 is fixedly connected to the side of the driving shaft 30 a, only by fixing both of the collar member 5 and the seal unit 4 (the retaining member 42) to the side of the same unit (the pump device 1), ease of assembly can be improved.

The seal unit 4 has the seal member 40 suppressing the leak of the working fluid from the insides of the pumps 31, 32 to the outside, the lip member 41 disposed in the axial direction of the seal member 40 and suppressing the outside leak of the working fluid, which further leaks from the seal member 40 to the outside, (also suppressing the entering of the dust from the outside), and the retaining member 42 retaining the seal member 40 and the lip member 41. Thus, the seal member 40 and the lip member 41 can be integrally connected together and the dual seal structure by the seal member 40 and the lip member 41 can be readily realized, thereby suppressing the axial direction size of the pump device 1 and improving assembly workability of the seal unit 4.

Further, as compared with a case where the pump housing 2 intervenes between the seal member 40 and the lip member 41 in the X-axis direction, by arranging both the seal member 40 and the lip member 41 with these members 40, 41 made contact with each other, although the same dual seal structure is employed, the axial direction size of the pump device 1 can be suppressed. In the embodiment 1, since an end surface, at the lip member 41 side, of the seal member 40 has a tapered surface whose angle is fitted to a shape of the lip (the lip member body 410) of the lip member 41, it is possible to prevent the lip from interfering with the seal member 40 (it is possible to prevent the seal member 40 from interfering with the lip), and also the lip member 41 and the seal member 40 can be set with these members 40, 41 arranged as close as possible to each other (with these members 40, 41 made contact with each other).

Here, there is a risk that when the seal member 40 rotates with respect to the pump housing 2 by the fact that the seal member 40 making contact with the outer circumference of the driving shaft 30 a rotates (or rotates by being dragged by the rotation of the driving shaft 30 a) together with the driving shaft 30 a, the elastic member (e.g. the rubber member) 401 will wear down or will be rubbed away (an outer circumferential part of the seal member 40 which makes contact with the inner circumferential surface of the pump housing 2 will wear down or will be rubbed away) then the sealing performance will be degraded. For this reason, it is preferable to suppress the rotation of the seal member 40 together with the driving shaft 30 a. Here, it is conceivable that a pin is fixedly set to the pump housing 2 (so as to extend or project toward the radial direction of the driving shaft 30 a) then the rotation of the seal member 40 is suppressed by connecting the seal member 40 to this pin. However, if the pin is provided as a rotation-stop member (as a whirl-stop member of the seal member 40), the axial direction size of the pump device 1 might be increased by a space required to provide this pin. In other words, there is a risk that an axial direction space required to set the seal member 40 will lengthen by the space required to provide this pin.

In contrast to this, in the pump device 1 in the embodiment 1, as a structure for suppressing the rotation of the seal member 40, the bottom portion 234 of the seal unit retaining hole 232 of the pump housing 2, which is formed to support (retain) the seal unit 4, is used. Hence, the increase in size of the pump device 1 in the axial direction can be suppressed.

More specifically, as the rotation-stop member, the disk member 6 (whose axial direction size is smaller than that of the above pin) is used. That is, the retaining member 42 of the seal member 40 is fixed to the pump housing 2 (fixed in the seal unit retaining hole 232). By the fact that the outer circumferential portion 63 of the disk member 6 set at the bottom portion 234 of the seal unit retaining hole 232 is sandwiched and supported between the retaining member 42 and the pump housing 2 (the bottom portion 234), the rotation of the disk member 6 with respect to the pump housing 2 is suppressed. The extending portion 62 of this disk member 6 is made contact with or touches an X-axis negative direction end surface of the seal member 40 (the seal member body 400), then the seal member 40 (the seal member body 400) is forced in the X-axis positive direction by an elastic force of the extending portion 62. The seal member 40 is consequently sandwiched and supported between the extending portion 62 of the disk member 6 and the bottom portion 420 of the retaining member 42 (through the lip member 41). With this configuration, the rotation of the seal member 40 with respect to the pump housing 2, i.e. the rotation of the seal member 40 together with the driving shaft 30 a (together with the collar member 5), can be suppressed.

That is, in the case where the pin is used to suppress the rotation of the seal member 40 together with the driving shaft 30 a as described above, a measure of rigidity of the pin, namely a measure of diameter (an X-axis direction size) of the pin, is required to receive a rotation force of the seal member 40.

In contrast to this, in the embodiment 1, by the fact that the rotation of the seal member 40 is suppressed using a pressing force (a frictional force) of the axial direction end surface of the seal member 40 (the seal member body 400), the X-axis direction size of the rotation-stop member (the axial direction space required to set the seal member 40 and the rotation-stop member) can be suppressed.

Here, it could be possible to remove the disk member 6. Instead, when fixing the retaining member 42 to the pump housing 2, the seal member 40 and the lip member 41 could be arranged so that these members 40, 41 are sandwiched and supported between the bottom portion 420 of the retaining member 42 and the bottom portion 234 of the seal unit retaining hole 232. That is, the X-axis negative direction end surface of the seal member 40 (the seal member body 400) is directly pressed against the bottom portion 234 of the seal unit retaining hole 232 by an axial direction pressing force of the press-fitted retaining member 42, and the frictional force is generated, then the rotation of the seal member 40 can be suppressed without using a special element as the rotation-stop member. Also in this case, not only the above function and effect can be obtained, but also the axial direction size of the pump device 1 can be reduced by a size equivalent to the removal of the disk member 6.

In the embodiment 1, since the disk member 6 is provided as the rotation-stop member, by using the disk member 6, so to speak, as a plate spring, a supporting force is easily generated, and the above function and effect can be ensured. That is, (in a case where the axial direction size of the retaining member 42 is fixed), by changing a protruding amount, in the X-axis positive direction, of the extending portion 62 of the disk member 6, a force by which the seal member 40 is forced (supported) can be adjusted as necessary. Further, a force by which the seal member 40 (the seal member body 400) is pressed (forced) in the radially inward direction toward the outer circumferential seal portion 50, namely a sealing force of the seal member 40, can be adjusted by a setting of the elastic member 401.

Here, also regarding the lip member 41, an axial direction one end (an X-axis positive direction end) of the elastic lip member body (the rubber lip member body) 410 is made contact with or touches the bottom portion 420 of the retaining member 42, then the lip member 41 is sandwiched and supported between the extending portion 62 of the disk member 6 and the bottom portion 420 of the retaining member 42 (through the seal member 40). With this configuration, rotation of the lip member 41 with respect to the pump housing 2 is suppressed. Further, when the elastic lip member body (the rubber lip member body) 410 is configured so that its axial direction other end (its X-axis negative direction end) is made contact with or touches the seal member 40, the rotation of the seal member 40 with respect to the pump housing 2 can be suppressed more effectively.

A force by which the lip member 41 (the lip member body 410) is pressed (forced) in the radially inward direction toward the outer circumferential seal portion 50, namely a sealing force of the lip member 41, can be adjusted by a setting of the lip member 41 when the lip member body 410 is bonded to the supporting member 411 by vulcanization bonding. With this configuration, it is possible to reduce a size of the lip member 41 (the seal unit 4), which can suppress the axial direction size of the pump device 1, while reducing parts count of the lip member 41.

That is, in a case of a general oil seal, a tip of the lip is pressed against a rotation shaft surface by an elastic member such as a spring, and a sealing force (a gripping force of the lip) is adjusted by the elastic member.

In contrast to this, in the case of the lip member 41 of the embodiment 1, the above elastic member is removed.

Instead, the lip member 41 has the sealing force by an initial setting state when forming the lip member body 410 by the vulcanization bonding. That is, this configuration is the one in which the sealing force is adjusted by the lip member body 410 itself.

Here, a function of a reinforcing ring that fixes the oil seal to a machine body side in the case of the general oil seal is obtained by the supporting member 411 in the case of the lip member 41 of the embodiment 1. In a state in which a radial direction movement of the supporting member 411 is restrained by the retaining member 42 fixed to the pump housing 2 (fixed in the seal unit retaining hole 232), the lip member body 410 bonded to the supporting member 411 generates a radial direction pressing force (the sealing force).

Here, the bottom portion 420 of the retaining member 42 could be used as the supporting member 411 of the lip member 41, then the retaining member 42 and the lip member 41 could be formed integrally with each other by bonding the lip member body 410 to the bottom portion 420 by the vulcanization bonding. In this case, it is possible to reduce the size of the seal unit 4, which can suppress the axial direction size of the pump device 1, while reducing parts count of the seal unit 4. In the embodiment 1, since the retaining member 42 and the lip member 41 are provided as the different members, a setting accuracy of the sealing force of the lip member 41 is increased, and the press-fitting process of the retaining member 42 can be easily performed.

The disk member 6 is set so as to be sandwiched and supported between the bottom portion 234 of the seal unit retaining hole 232 and the seal unit 4, and has the penetration hole (the circle hole) 60 where the driving shaft 30 a having the smaller diameter penetrates. By the fact that the inner rim 61 of the penetration hole 60 of the disk member 6 and the stepped portion 302 of the driving shaft 30 a interfere with each other (are made contact with or touch each other), a movement, to the axial direction one side (in the X-axis positive direction), of the driving shaft 30 a (falling-out or coming-out of the driving shaft 30 a) is restrained. Therefore, a structure for restraining an axial direction position of the driving shaft 30 a is simplified, then the reduction in the size of the pump device 1 can be achieved.

For instance, it is also conceivable that the axial direction movement of the driving shaft 30 a is restrained by the bearing (the first bearing 7 a and/or the third bearing 9 a) that supports the driving shaft 30 a. More specifically, it is conceivable that the above bearing is formed by an inner race, an outer race and rolling elements provided between these races, then the inner race is press-fitted to the driving shaft 30 a and the outer race is set with the outer race restraining the movement of the driving shaft 30 a in the axial direction. In this case, however, the assembly workability is deteriorated due to an addition of the press-fitting process of the inner race, also the size of the pump device 1 may be increased due to an increase of the size of the bearing.

In contrast to this, in the embodiment 1, since the axial direction movement of the driving shaft 30 a is restrained not by the bearing, but by the disk member 6, the reduction in the size of the pump device 1 can be achieved while ensuring good assembly workability. Here, if the bearings 7 a, 9 a are removed and the pump housing 2 itself serves as a bearing, further reduction in the size of the pump device 1 can be achieved.

Furthermore, for example, it is also conceivable that the axial direction movement of the driving shaft 30 a is restrained by a contact of X-axis positive direction side surfaces of the pins 33 a, 34 a by which the first and second drive gears 31 a, 32 a are joined to the driving shaft 30 a in the whirl-stop connecting manner and the side plate 312, 322 respectively. However, in this case, there is a risk that the pins 33 a, 34 a and the side plate 312, 322 will wear down or will be rubbed away and also the liquid-tightness between the low-pressure chamber and the high-pressure chamber by the side plate 312, 322 will decrease.

In contrast to this, in the embodiment 1, since the axial direction movement of the driving shaft 30 a is restrained not by the pins 33 a, 34 a, but by the stepped portion 302, the above problem can be avoided.

On the other hand, as for a movement, to the axial direction other side (in the X-axis negative direction), of the driving shaft 30 a, by the fact that the driving shaft 30 a and the pump housing 2 (the bottom portion 21 a of the first housing 21 which faces an X-axis negative direction end portion of the driving shaft 30 a in the X-axis direction) interfere with each other (are made contact with or touch each other), the movement, in the X-axis negative direction, of the driving shaft 30 a is restrained. That is, in the embodiment 1, since the first housing 21 is provided, the pump device 1 can be handled as one unit, then the assembly workability is improved. In addition, since the first and second shaft housing holes 210 a, 210 b of the first housing 21 are covered or closed by the bottom portion 21 a, it is possible to suppress the leak of the working fluid from the inside of the pump housing 2 (from the first and second shaft housing holes 210 a, 210 b) without providing the special element such as the seal member 40. Additionally, an X-axis direction size of the housing 110 of the hydraulic unit 11 is set to be smaller than the X-axis direction size of the pump device 1, then it is possible to reduce the size of the brake apparatus 10.

Further, since the first shaft housing hole 210 a of the first housing 21 is covered or closed by the bottom portion 21 a, the bottom portion 21 a serves as a stopper of the driving shaft 30 a. It is therefore possible to restrain the movement, in the X-axis negative direction, of the driving shaft 30 a without providing a special stopper element. This also brings about the reduction of parts count.

Here, the movement, to the axial direction other side (in the X-axis negative direction), of the driving shaft 30 a could be restrained by the fact that the X-axis negative direction end portion (end surface) of the collar member 5 and the inner rim 61 of the penetration hole 60 of the disk member 6 interfere with each other.

In the embodiment 1, by forming the disk member 6 as the single-piece member by pressing, productivity can be increased. The disk member 6 could be formed by a cutting process.

As explained above, the seal member 40 and the lip member 41 are fixedly connected through the retaining member 42, and the seal member 40 and the lip member 41 are set so as to be sandwiched and supported between the bottom portion 420 of the retaining member 42 and the bottom portion 234 of the seal unit retaining hole 232 (the disk member 6) when fixing the retaining member 42 to the pump housing 2. Ease of assembly of the seal unit 4 is thus improved, and also an axial direction size of the seal unit 4 as a whole is suppressed. Further, it is possible to suppress the rotation of the seal unit 4 (the rotation of the sealing forces of the seal member 40 and the lip member 41) together with the driving shaft 30 a while securing the sealing forces of the seal member 40 and the lip member 41.

Furthermore, the driving shaft 30 a and the motor rotation shaft 120 are connected together in the seal unit retaining hole 232, and the outer circumferential seal portion 50 provided at the outer circumferential side of this connecting portion makes sliding contact with the seal unit 4 (the seal member 40 and the lip member 41). The axial direction size of the pump device 1 can therefore be suppressed.

Moreover, by setting an axial direction size of the seal unit retaining hole 232 to the minimum required to set the seal unit 4 and the disk member 6 (to a total of the axial direction size of the retaining member 42 and a thickness of the outer circumferential portion of the disk member 6), the axial direction size of the pump device 1 can be suppressed more effectively.

In addition, by the fact that the retaining member 42 is press-fixed to the seal unit retaining hole 232, as compared with the other fixing manner, no special element or no special structure for the fixing is required, thereby reducing parts count and achieving the size reduction of the pump device 1.

Additionally, by forming the bottom portion 420 integrally with the retaining member 42, the seal unit 4 can be formed as a simple unit and ease of its assembly is improved. Also by the fact that the seal member 40 and the lip member 41 are sandwiched using this bottom portion 420, this does not any special element to sandwich these members 40, 41, and reduces the parts count.

Effect of Embodiment 1

The pump device 1 of the embodiment 1 has the following effects.

(1) A pump device (1) having a motor rotation shaft (120) and a pump rotation shaft (30; driving shaft 30 a) whose end portion (300) is connected to an end portion (121) of the motor rotation shaft (120) and which drives a pump unit (3), the pump device (1) comprises: an outer circumferential seal portion (50) that is arranged at either one or both of radially outer sides of the end portion (300) of the driving shaft (30 a) and the end portion (121) of the motor rotation shaft (120) so as to overlap with either one or both of the end portion (300) of the driving shaft (30 a) and the end portion (121) of the motor rotation shaft (120) in axial directions of the driving shaft (30 a) and the motor rotation shaft (120) and has an outer circumferential seal surface (500); and a seal unit (4) that makes sliding contact with the outer circumferential seal portion (50).

Since the end portion 300 and/or the end portion 121, the outer circumferential seal portion 50 and the seal unit 4 are arranged in the radial direction, it is possible to suppress the increase in size of the pump device 1 in the axial direction (in other words, it is possible to achieve the reduction of the axial direction size of the pump device 1).

(2) In the pump device (1), the seal unit (4) is set in an area ranging from the end portion (300) of the pump rotation shaft (30 a) to the end portion (121) of the motor rotation shaft (120) in the X-axis direction.

Therefore, the axial direction size of the pump device 1 can be suppressed more effectively.

(3) In the pump device (1), a collar member (5) is provided at an outer circumference of the end portion (300) of the pump rotation shaft (30 a) and at an outer circumference of the end portion (121) of the motor rotation shaft (120) with the collar member (5) ranging from the end portion (300) of the pump rotation shaft (30 a) to the end portion (121) of the motor rotation shaft (120), and the outer circumferential seal portion (50) is formed at an outer circumference of the collar member (5).

It is therefore possible to easily form the outer circumferential seal portion 50.

(4) In the pump device (1), the collar member (5) is fixedly connected to the pump rotation shaft (30 a).

Thus, ease of assembly of the pump device 1 and the motor 12 can be improved.

(5) In the pump device (1), the collar member (5) is press-fixed to the pump rotation shaft (30 a), and is connected to the motor rotation shaft (120) in a whirl-stop connecting manner.

Thus, ease of assembly of the pump device 1 and the motor 12 can be improved.

Embodiment 2

In the embodiment 1, the collar member 5 is fixed by the press-fixing. However, in a pump device 1 of an embodiment 2, the collar member 5 is fixed to the end portion 300 of the driving shaft 30 a with a screw etc.

FIG. 3 is an axial direction sectional view of the pump device 1 of the embodiment 2. The X-axis positive direction side end portion 300 of the driving shaft 30 a has a seal member setting portion 303 and a male screw portion 304. The seal member setting portion 303 is formed at an X-axis negative direction side of the end portion 300. The seal member setting portion 303 is provided, at an outer circumference thereof, with an annular seal groove (a ring groove) 305. The seal groove 305 houses therein an O-ring 306 as a seal member.

The male screw portion 304 is formed at an X-axis positive direction side of the end portion 300 (the seal member setting portion 303), and a diameter of the male screw portion 304 is set to be smaller than that of the seal member setting portion 303. A male thread is formed at an outer circumference of the male screw portion 304.

The driving shaft insertion hole 51 of the collar member 5 has a seal surface 510 and a female screw portion 511. The seal surface 510 is formed at an X-axis negative direction side of the driving shaft insertion hole 51, and its diameter is set to be slightly greater than that of the end portion 300 (the seal member setting portion 303). The O-ring 306 is made contact with or touches an inner circumference of the seal surface 510.

The female screw portion 511 is formed at an X-axis positive direction side of the driving shaft insertion hole 51 (the seal surface 510), and a diameter of the female screw portion 511 is set to be smaller than that of the seal surface 510. A female thread is formed at an inner circumference of the female screw portion 511.

By the fact that the female screw portion 511 is screwed onto the male screw portion 304, the collar member 5 is fixed to the end portion 300 of the driving shaft 30 a. Further, by the fact that the end portion 121 of the motor rotation shaft 120 is inserted into the motor rotation shaft insertion hole 52 of the collar member 5, the collar member 5 is connected to the motor rotation shaft 120 in the whirl-stop connecting manner.

Furthermore, by the fact that the O-ring 306 makes contact with or touches a bottom portion of the seal groove 305 and the seal surface 510 with the O-ring 306 shrunk or compressed in the radial direction, the 0-ring 306 liquid-tightly seals a gap between the collar member 5 (the driving shaft insertion hole 51) and the driving shaft 30 a (the end portion 300).

In the embodiment 2, although a diameter of the penetration hole 60 of the disk member 6 is set to be greater than that of the driving shaft 30 a (the large diameter side of the stepped portion 302) so that the inner rim 61 of the penetration hole 60 and the stepped portion 302 of the driving shaft 30 a do not interfere with each other, the same configuration or setting as the embodiment 1 could be used.

Each component is indicated by the same reference sign as that of the embodiment 1 in the drawings, and its explanation is omitted here.

By the fact that the collar member 5 is screwed onto the male screw portion 304 of the driving shaft 30 a, the collar member 5 is fixedly connected to the driving shaft 30 a. Since the gap between the collar member 5 (the driving shaft insertion hole 51) and the driving shaft 30 a (the end portion 300) is sealed by the O-ring 306, the liquid-tightness is increased, and the leak of the working fluid from the inside of the pump device 1 to the outside can be suppressed.

Here, it is also possible to set the seal member (the O-ring 306) not at the outer circumference of the driving shaft 30 a, but at the inner circumference of the collar member 5 or between a stepped portion (between the seal surface 510 and the female screw portion 511) of the collar member 5 and the a stepped portion (between the seal member setting portion 303 and the male screw portion 304) of the driving shaft 30 a.

The other function and effect are the same as those of the embodiment 1, and their explanations are omitted here.

Embodiment 3

In the embodiment 1, the collar member 5 is provided as the different member from the driving shaft 30 a. However, in a pump device 1 of an embodiment 3, the collar member 5 is formed integrally with the driving shaft 30 a (the collar member 5 is formed as an integral part of the driving shaft 30 a).

FIG. 4 is an axial direction sectional view of the pump device 1 of the embodiment 3. By the fact that the collar member 5 is formed integrally with the driving shaft 30 a, the collar member 5 is fixedly connected to the driving shaft 30 a. Here, in the embodiment 3, the stepped portion 302 is not provided at the driving shaft 30 a, then the driving shaft 30 a and the inner rim 61 of the disk member 6 do not interfere with each other when the driving shaft 30 a moves to the X-axis positive direction side.

Each component is indicated by the same reference sign as that of the embodiment 1 in the drawings, and its explanation is omitted here.

The collar member 5 is formed integrally with the driving shaft 30 a, thereby reducing the parts count. Here, a diameter of the collar member 5 might be set to be smaller than that of the driving shaft 30 a, then assembly workability of the pump device 1 can be improved. In this case, it is also possible to provide the stepped portion 302 same as the embodiment 1, then the X-axis positive direction movement of the driving shaft 30 a is restrained.

In the embodiment 3, since the diameter of the collar member 5 is set to be greater than that of the driving shaft 30 a, rigidity or durability of the collar member 5 to which a torque of the motor rotation shaft 120 is inputted can be increased.

The other function and effect are the same as those of the embodiment 1, and their explanations are omitted here.

Other Embodiment

The present invention is not limited to the above embodiments. For instance, the configuration or structure of the pump housing 2 is not limited to those of the above embodiments. It could be possible to form the second pump housing hole 222 in the third housing 23. Further, the pump device 1 is not limited to the external gear pump, the pump device 1 could be an internal gear pump. Also the pump is not limited to the gear pump, but a vane pump is also employed.

The above embodiments can produce advantageous effects as described above. In addition to those, modified examples having substantially the same effects as the above embodiments will be explained below.

(6) In the pump device (1), the collar member (5) is formed integrally with the pump rotation shaft (30 a), and is connected to the motor rotation shaft (120) in a whirl-stop connecting manner.

It is therefore possible to reduce the parts count.

(7) In the pump device (1), the pump rotation shaft (30 a) has, at one end side thereof, a male screw portion (304), and the collar member (5) has a female screw portion (511) that is screwed onto the male screw portion (304), and is connected to the motor rotation shaft (120) in a whirl-stop connecting manner.

Thus, ease of assembly of the pump device 1 and the motor 12 can be improved.

(8) In the pump device (1), the pump rotation shaft (30 a) has an O-ring (306) that seals a gap between the collar member (5) and the pump rotation shaft (30 a) and a ring groove (305) that is formed at the pump rotation shaft (30 a) and houses therein the O-ring (306).

The liquid-tightness can therefore be increased.

(9) In the pump device (1), the seal unit (4) has; a seal member (40) that suppresses a leak of working fluid from an inside of the pump device (1) to the outside; a lip member (41) that is disposed in an axial direction of the seal member (40) and suppresses an external leak of the working fluid, which further leaks from the seal member (40) to the outside; and a retaining member (42) that retains the seal member (40) and the lip member (41).

The seal member 40 and the lip member 41 can be integrally connected together and the dual seal structure by the seal member 40 and the lip member 41 can be readily realized.

(10) In the pump device (1), the seal unit (4) is retained, through the retaining member (42), in a seal unit retaining hole (232) that is formed in an outer peripheral area of an end portion of a housing (2; 23).

It is thus possible to suppress the increase in size of the pump device 1 in the axial direction.

(11) In the pump device (1), the pump rotation shaft (30 a) has a stepped portion (302) that is formed by a fact that a diameter of the end portion (300) side of the pump rotation shaft (30 a) is formed to be smaller, and a disk member (6) is provided so as to be sandwiched and supported between a bottom portion (234) of the seal unit retaining hole (232) and the seal unit (4), and the disk member (6) has a penetration hole (60) where the pump rotation shaft (30 a) having the smaller diameter penetrates, and wherein by a fact that an inner rim (61) of the penetration hole (60) of the disk member (6) and the stepped portion (302) of the pump rotation shaft (30 a) interfere with each other, a movement of the pump rotation shaft (30 a) to an axial direction one side is restrained.

The structure for restraining the axial direction position of the driving shaft 30 a can be simplified.

(12) A pump device comprises: a motor rotation shaft (120); a pump rotation shaft (30; 30 a) that is connected to the motor rotation shaft (120) through a connecting portion (301) of the pump rotation shaft (30; 30 a) and drives a pump unit (3); and a seal unit (4) that suppresses a leak of working fluid from the pump unit (3) along an outer circumference of the pump rotation shaft (30; 30 a), and the connecting portion (301) of the pump rotation shaft (30; 30 a) is located at a radially inner side of the seal unit (4)

By arranging the connecting portion 301 and the seal unit 4 in the radial direction, the increase in size of the pump device 1 in the axial direction can be suppressed.

(13) In the pump device (1), a collar member (5) is provided at an outer circumference of the connecting portion (301), and the seal unit (4) makes sliding contact with an outer circumference of the collar member (5) and suppresses the leak of the working fluid.

It is therefore possible to easily form the outer circumferential seal portion 50.

(14) In the pump device (1), the collar member (5) is press-fixed to the pump rotation shaft (30 a).

It is therefore possible to reduce the parts count.

(15) In the pump device (1), the collar member (5) and the motor rotation shaft (120) are connected together in a whirl-stop connecting manner.

Thus, ease of assembly of the pump device 1 and the motor 12 can be improved.

(16) In the pump device (1), the collar member (5) is formed integrally with the pump rotation shaft (30 a), and the collar member (5) and the motor rotation shaft (120) are connected together in a whirl-stop connecting manner.

It is therefore possible to reduce the parts count.

(17) In the pump device (1), the seal unit (4) has; a seal member (40) that suppresses a leak of working fluid from an inside of the pump device (1) to the outside; a lip member (41) that is disposed in an axial direction of the seal member (40) and suppresses an external leak of the working fluid, which further leaks from the seal member (40) to the outside; and an annular retaining member (42) that retains an outer peripheral side of the seal member (40) and an outer peripheral side of the lip member (41).

The seal member 40 and the lip member 41 can be integrally connected together and the dual seal structure by the seal member 40 and the lip member 41 can be readily realized.

(18) A pump device comprises: a housing (2); a motor (12) that is fixed to the housing (2) and drives a pump unit (3) provided in the housing (2), the motor (12) having a motor rotation shaft (120) that is connected to a pump rotation shaft (30; 30 a) of the pump unit (3) through a connecting portion (301) of the pump rotation shaft (30; 30 a) and drives the pump unit (3); a cylindrical collar member (5) that covers the connecting portion (301) of the pump rotation shaft (30; 30 a); a seal unit (4) that makes sliding contact with an outer circumferential surface of the cylindrical collar member (5); and a seal unit retaining hole (232) that is formed in the housing (2; 23) and retains therein the seal unit (4).

It is possible to suppress the increase in size of the pump device 1 in the axial direction.

(19) In the pump device (1), the collar member (5) is press-fixed to the pump rotation shaft (30 a), and is connected to the motor rotation shaft (120) in a whirl-stop connecting manner.

Thus, ease of assembly of the pump device 1 and the motor 12 can be improved.

(20) In the pump device (1), the pump rotation shaft (30 a) has a stepped portion (302) that is formed by a fact that a diameter of the end portion (300) side of the pump rotation shaft (30 a) is formed to be smaller, and a disk member (6) is provided so as to be sandwiched and supported between a bottom portion (234) of the seal unit retaining hole (232) and the seal unit (4), and the disk member (6) has a penetration hole (60) where the pump rotation shaft (30 a) having the smaller diameter penetrates, and wherein by a fact that an inner rim (61) of the penetration hole (60) of the disk member (6) and the stepped portion (302) of the pump rotation shaft (30 a) interfere with each other, a movement of the pump rotation shaft (30 a) to an axial direction one side is restrained, and by a fact that the pump rotation shaft (30 a) and the housing (2) interfere with each other, a movement of the pump rotation shaft (30 a) to an axial direction other side is restrained.

Thus, restraint of the position of the driving shaft 30 a can be easily made.

The entire contents of Japanese Patent Application No. 2012-148264 filed on Jul. 2, 2012 are incorporated herein by reference.

Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in light of the above teachings. The scope of the invention is defined with reference to the following claims. 

What is claimed is:
 1. A pump device having a motor rotation shaft and a pump rotation shaft whose end portion is connected to an end portion of the motor rotation shaft and which drives a pump unit, the pump device comprising: an outer circumferential seal portion that is arranged at either one or both of radially outer sides of the end portion of the pump rotation shaft and the end portion of the motor rotation shaft so as to overlap with either one or both of the end portion of the pump rotation shaft and the end portion of the motor rotation shaft in axial directions of the pump rotation shaft and the motor rotation shaft and has an outer circumferential seal surface; and a seal unit that makes sliding contact with the outer circumferential seal portion.
 2. The pump device as claimed in claim 1, wherein: the seal unit is set in an area ranging from the end portion of the pump rotation shaft to the end portion of the motor rotation shaft in the X-axis direction.
 3. The pump device as claimed in claim 1, wherein: a collar member is provided at an outer circumference of the end portion of the pump rotation shaft and at an outer circumference of the end portion of the motor rotation shaft with the collar member ranging from the end portion of the pump rotation shaft to the end portion of the motor rotation shaft, and the outer circumferential seal portion is formed at an outer circumference of the collar member.
 4. The pump device as claimed in claim 3, wherein: the collar member is fixedly connected to the pump rotation shaft.
 5. The pump device as claimed in claim 4, wherein: the collar member is press-fixed to the pump rotation shaft, and is connected to the motor rotation shaft in a whirl-stop connecting manner.
 6. The pump device as claimed in claim 4, wherein: the collar member is formed integrally with the pump rotation shaft, and is connected to the motor rotation shaft in a whirl-stop connecting manner.
 7. The pump device as claimed in claim 4, wherein: the pump rotation shaft has, at one end side thereof, a male screw portion, and the collar member has a female screw portion that is screwed onto the male screw portion, and is connected to the motor rotation shaft in a whirl-stop connecting manner.
 8. The pump device as claimed in claim 7, wherein: the pump rotation shaft has an O-ring that seals a gap between the collar member and the pump rotation shaft and a ring groove that is formed at the pump rotation shaft and houses therein the O-ring.
 9. The pump device as claimed in claim 4, wherein: the seal unit has; a seal member that suppresses a leak of working fluid from an inside of the pump device to the outside; a lip member that is disposed in an axial direction of the seal member and suppresses an external leak of the working fluid, which further leaks from the seal member to the outside; and a retaining member that retains the seal member and the lip member.
 10. The pump device as claimed in claim 9, wherein: the seal unit is retained, through the retaining member, in a seal unit retaining hole that is formed in an outer peripheral area of an end portion of a housing.
 11. The pump device as claimed in claim 10, wherein: the pump rotation shaft has a stepped portion that is formed by a fact that a diameter of the end portion side of the pump rotation shaft is formed to be smaller, and a disk member is provided so as to be sandwiched and supported between a bottom portion of the seal unit retaining hole and the seal unit, and the disk member has a penetration hole where the pump rotation shaft having the smaller diameter penetrates, and wherein by a fact that an inner rim of the penetration hole of the disk member and the stepped portion of the pump rotation shaft interfere with each other, a movement of the pump rotation shaft to an axial direction one side is restrained.
 12. A pump device comprising: a motor rotation shaft; a pump rotation shaft that is connected to the motor rotation shaft through a connecting portion of the pump rotation shaft and drives a pump unit; and a seal unit that suppresses a leak of working fluid from the pump unit along an outer circumference of the pump rotation shaft, and the connecting portion of the pump rotation shaft being located at a radially inner side of the seal unit.
 13. The pump device as claimed in claim 12, wherein: a collar member is provided at an outer circumference of the connecting portion, and the seal unit makes sliding contact with an outer circumference of the collar member and suppresses the leak of the working fluid.
 14. The pump device as claimed in claim 13, wherein: the collar member is press-fixed to the pump rotation shaft.
 15. The pump device as claimed in claim 12, wherein: the collar member and the motor rotation shaft are connected together in a whirl-stop connecting manner.
 16. The pump device as claimed in claim 13, wherein: the collar member is formed integrally with the pump rotation shaft, and the collar member and the motor rotation shaft are connected together in a whirl-stop connecting manner.
 17. The pump device as claimed in claim 12, wherein: the seal unit has; a seal member that suppresses a leak of working fluid from an inside of the pump device to the outside; a lip member that is disposed in an axial direction of the seal member and suppresses an external leak of the working fluid, which further leaks from the seal member to the outside; and an annular retaining member that retains an outer peripheral side of the seal member and an outer peripheral side of the lip member.
 18. A pump device comprising: a housing; a motor that is fixed to the housing and drives a pump unit provided in the housing, the motor having a motor rotation shaft that is connected to a pump rotation shaft of the pump unit through a connecting portion of the pump rotation shaft and drives the pump unit; a cylindrical collar member that covers the connecting portion of the pump rotation shaft; a seal unit that makes sliding contact with an outer circumferential surface of the cylindrical collar member; and a seal unit retaining hole that is formed in the housing and retains therein the seal unit.
 19. The pump device as claimed in claim 18, wherein: the collar member is press-fixed to the pump rotation shaft, and is connected to the motor rotation shaft in a whirl-stop connecting manner.
 20. The pump device as claimed in claim 19, wherein: the pump rotation shaft has a stepped portion that is formed by a fact that a diameter of the end portion side of the pump rotation shaft is formed to be smaller, and a disk member is provided so as to be sandwiched and supported between a bottom portion of the seal unit retaining hole and the seal unit, and the disk member has a penetration hole where the pump rotation shaft having the smaller diameter penetrates, and wherein by a fact that an inner rim of the penetration hole of the disk member and the stepped portion of the pump rotation shaft interfere with each other, a movement of the pump rotation shaft to an axial direction one side is restrained, and by a fact that the pump rotation shaft and the housing interfere with each other, a movement of the pump rotation shaft to an axial direction other side is restrained. 